Due to increased competition and eroding revenue margins, service providers are demanding better yields from their network infrastructure. In response to this demand, the next generation of transport networks must provide mechanisms for creating a number of different classes of service (CoS), while ensuring that the cost of each service is proportional to the revenue it generates. Thus, bandwidth-on-demand for event driven traffic, or creation of bandwidth brokering services are just a few of the new optical layer services that can be created. Attributes such as protection level, latency, priority, transparency, and diversity may also be used to define optical services. These could be either general characteristics of the network or specific characteristics of a connection. As such, CoS considerations need to be taken into account both when planning a network, when routing an individual connection, and when collecting the revenue.
These demands have exposed a number of weaknesses with respect to the current optical networks and their mode of operation.
Traditional WDM (wavelength division multiplexed) networks have a point-to-point configuration, with electrical cross-connects (EXC) provided at all switching nodes. This network architecture allows fairly limited optical layer service offerings. In addition, a point-to-point architecture is very difficult to scale. Thus, the nodes complexity grows with the number of the channels, such that provisioning and engineering operations become more complex, involving extensive design, simulation, engineering and testing, which activities increase the service activation time (SAT).
This large service activation time leads to loss of revenue from a number of perspectives. First, losing contracts due to turn-up time has driven direct loss of sales. More strategically however, it has led to situations where traditional carrier customers (ISPs, etc) have concluded they would be better off owning and operating their own infrastructure. Naturally, once this infrastructure is in place, these traditional customers become competitors, providing services of their own. If the service activation time could be reduced, a carrier would have a significant competitive advantage, increasing its market share and the ability to keep potential competitors out of the market.
Another disadvantage of the current network architecture is the lack of flexibility. Thus, a point-to-point architecture does not have the ability to turn up/down bandwidth rapidly, or/and to provide bandwidth optimized for the data layer needs, even if the equipment for the new service is in place.
To make-up for the lack of flexibility and scalability, there is a current trend to deploy “intelligent” optical networks, where the intelligence resides within the network management. There are many levels of management within any communication network, from element managers controlling individual network elements, to customer billing software, activation and provisioning software and network management systems MNS. Most often, a network management system contains multiple software management platforms for each service and each specific vendor's equipment. However, the growth of nodal complexity discussed above results in increased network management complexity. If a service requires access to multiple network providers' infrastructures, further complications arise when different platforms need to communicate with each other. In addition, the conventional network management systems allow management at the network element granularity, and allow control and monitoring of a limited number of physical layer parameters.
Still another drawback of the current network management systems is the inability to maintain an accurate inventory of the network equipment. Traditionally, the network administrator maintains various operations and support systems, which include an inventory of the equipment making-up the network. For example, TIRKS (Trunks Integrated Records Keeping System), which was developed to mechanize the circuit provisioning process, is often used as the master record keeping system for the data networks. Based on network inventory and connectivity data collected manually at various sites, the TIRKS database outputs appropriate information for programming the nodes of the network. TIRKS system supports now the full range of transmission technologies, such as SONET, European digital hierarchy standards (SDH), digital circuitry hierarchy (DS0, DS1, DS3), and analog voice circuits.
However, such conventional inventory systems have a number of drawbacks. Thus, they need to be integrated with the NMS, by building a user specific interface for each proprietary NMS. Often the inventory does not reflect accurately the network make-up, as the data collection and the updates are entered manually (an up-to-down approach). Also, the information is available network-wide only after it is effectively entered and the inventory system is re-loaded. These systems do not accommodate variants reflecting changes in the operation of a certain device after the equipment has been coded into the inventory, and especially if the equipment is assigned for service. In addition, the conventional inventory systems have a network element level granularity.
As a result, the point-to-point architecture offers a very limited range of services and does not allow for reducing the service activation time (SAT) for this limited range of services. On the contrary, as the network scales-up, the SAT (and the cost) becomes increasingly unacceptable. Today, a typical waiting time for new optical services in a point-to-point network is more than of 120 days.
There is a trend to transit from the point-to-point configurations to a new architecture, where the channels are routed, switched and monitored independently. This new type of network is designed with a view to provide the networks with flexibility, scalability and differentiated CoS levels at the physical layer (channel level).
Since such a wavelength switched network operates on different principles than the point-to-point network, the network management of these networks requires a new architecture. For example, because most of the hardware in a telecommunications network is subject to changing conditions and changing configurations, it is important to dynamically adapt network operation to these changes. Thus, achieving true agility is possible if the network resources, such as terminals, regenerators and wavelengths, are dynamically and automatically allocated to various connections. This in turn implies accurate knowledge of current network resources availability. Also, as the connections are set-up and removed at arbitrary moments and the number of channels on any fiber link changes constantly, each connection must be controlled independently. This means that the performance of the optical modules along each connection needs to be known and accurately controlled.
There is a need to provide a network with a topology autodiscovery system, which provides real-time, accurate knowledge of the network resources, for enabling true agility at the physical layer.